Apparatus for eliminating lint in discharge duct of clothes driers



Oct. 8., 1957 E. s. PETTYJOHN 2,809,025

. APPARATUS FOR ELIMINATING LINT IN DISCHARGE DUCT OF CLOTHES DRIERSFiled Dec. 6. 1954 ATTORNEYS.

United States Pate APPARATUS FOR ELIMINATING LINT IN DIS- CHARGE DUCT OFCLOTHES DRIERS Elmore S. Pettyjohn, Evanston, Ill., assignor toInstitute of Gas Technology, Chicago, 111., a corporation of IllinoisApplication December 6, 1954, Serial No. 473,310

7 Claims. (Cl. 263-33) This invention relates to an apparatus foreliminating lint entrained in the gas stream discharged from clothesdriers and for lowering the relative humidity of the gas stream toprevent condensation.

It has been proposed heretofore to heat the exit gas stream in thedischarge duct leading from the drier to a temperature sufficiently highto incinerate the lint entrained therein and simultaneously to lower therelative humidity of the gas to eliminate condensation. It has beenfound, however, that a relatively large amount of heat is required to doan effective job in accordance with this method. To be economicallyfeasible the equipment required for accomplishing these objectives mustadd only a relatively small sum to the cost of the drier and must notappreciably increase the cost of operation.

It is a general object of this invention to provide an apparatus forincinerating the lint and lowering the relative humidity of the exit gasstream which requires a relatively small amount of heat, utilizes thecontrol elements already a part of the drier, and can be installed withonly minor modifications of typical production-model drier structures.

A further object is to provide an apparatus of the nature indicated forgas operated driers which utilizes hot combustion gases diverted fromthe main gas burner in the drier, thus eliminating the necessity ofadding a separate burner, extra pilots and safety controls.

Another object is to provide means for carrying out incineration of theentrained lint continuously and without noticeable smoke production.

These and other objects will become apparent from the followingdescription and are pointed out more clearly in the appended claims.

In the drawings:

Figure 1 is a rear elevational view of a conventional drier which hasbeen modified to incorporate the apparatus of this invention;

Figure 2 is a sectional view taken along the line 22 of Figure 1;

Figure 3 is an enlarged sectional view taken along the line 3-3 ofFigure 1 showing details of the incinerating apparatus of the invention;and

Figure 4 is an exploded perspective view of the essential elementsrequired for incineration of the lint, which are located within the exitduct.

The invention comprises continuously separating the lint from theflowing gas stream and igniting the separated lint by bringing it intocontact with a flame and/ or hot gases or heating elements maintained atabove the ignition temperature of the lint. By separating the lint fromthe gas stream it becomes unnecessary to raise the temperature of theentire stream to the lint ignition temperature, which means that thetotal heat required for complete incineration is only a fraction, sayless than -l5%, of the amount required to bring the whole stream toignition temperature.

Referring now to the drawings, the drier is indicated generally by thenumeral 10 and comprises the usual Patented Oct. 8, 1957' elements,including frame members 12, an enclosed compartment 18, a perforateddrum 14 for tumbling the clothes rotatably mounted within thecompartment, a motor 16 for driving the drum and the air blower, thenecessary ducts for bringing air into and out of the compartment 18, anda gas burner 22 for heating the air. As best shown in Figure 2, a duct20 beneath the compartment communicates with the room through a grill(not shown) at the front of the machine and serves to conduct air fromthe room into the compartment 18 through duct 24 and the opening 26. Thegas burner 22 is mounted centrally within the duct 20. The air flowsover the burner 22, whereupon the temperature thereof is raised, andthen up through the duct 24 and into the compartment 18 where it absorbsthe moisture from the clothes and takes on a certain amount of lintwhich rubs off the clothes during tumbling.

Moisture-laden air carrying entrained lint escapes from the compartment18 through outlet opening 28 in the rear panel of the compartment. Itwill be understood that the location of the air inlet and outletopenings is not critical and will vary with the construction of thedrier. A generally L-shaped discharge duct 30 connects to the opening 28and extends upwardly and laterally across the back of the machine. Anexhaust blower 32 connects at its intake side to the end of the duct 30,the blower discharging to the atmosphere through any suitable conduit(not shown) connected to the blower outlet 34.

For collecting lint from the air stream a screen 40 is mounted on acircular support 42 adapted to fit within the duct. The screen support42 is fixed to the end of a rod 44 journalled in a bracket 43 secured tothe inside wall of the duct 30. The rod 44 pierces the duct 30, asindicated at 46, and is coupled to a small electric motor 43 of thevariety employed for clocks. Motor 48 utilizes the, same source of powersupply as the motor 16. If desired, motor 16 may be used to drive thescreen support 42 through a suitable speed reducer (not shown). Thescreen 40 may be replaced by any suitable means for trapping the lintwhile permitting the gas to flow freely through the duct. A perforatedplate might serve perfectly well for this purpose. The concentrated heatsource required to burn the lint from the rotating screen is provided inthe form of a burner or by-pass tube 50 which extends from the screen4-0 through the duct 24 to the burner 22 in the duct 20. The tube 50 issupported by the wall of the duct 24 through sealed opening 25 and by abracket 54, depending from the upper surface of duct 20. The by-passtube 50 terminates in a slit 52 at one end thereof and is so disposedwithin the duct 30 that the slit 52 lies parallel to a radius of thescreen 40 and is slightly spaced therefrom. The opposite end of the tube50 extends into the duct 20 through the opening 23 and terminatesadjacent the main gas burner 22 for conducting burning gases from themain burner flame through the tube to the screen 40. The duct 30 ismaintained under reduced pressure by the downstream blower 32, whichcauses the burning gases to be drawn through the tube 50.

To insure collection of all the lint on the screen and to prevent lintfrom accumulating on the edges of the screen support 42 and the interiorwall of the duct 30 adjacent thereto, a frusto-conical sleeve or collar56 is incorporated within the duct 30. The restriction in the diameterof the duct 30 resulting from incorporation of the sleeve 56 directs thegas flow through the screen so that the lint does not pass between theouter edge of the screen support 42 and the duct 30. Preferably, thescreen support 42 has a flange 45 which extends between the sleeve 56and the duct 30.

The blower 32 fixed to the end of the duct 30 may be operated by themotor 16, which serves to rotate the drum 3 within the driercompartment. This blower is of sufficient capacity to draw a slightvacuum on the compartment 18 and the entire ductwork system so that airis constantly flowing from the room into the drier and is dischargedfrom 'the drier to the out-'of doo'rs through the outlet 34 of the-blower.

In operation, the screen 40 is rotated at a uniform speed of about onerevolution per minute; the speed of rotation is not critical. Byrotating the screen continuously, the lint which builds up thereon isburned off continuously in small quantities so that no noticeable smokeis generated and discharged from the ductwork. If desired, the burnermouth may be adapted to move past a stationary screen. It is importantonly that there be relative motion between the lint collector and theflame.

Although in the construction illustrated I have shown an apparatus whichutilizes gas as the source of heat, it will be understood thatelectricity may also be used to burn the lint. For example, the screenmay be made of nichrome Wire connected to a source of electrical energyso that it will heat up to incandescence and burn the lint immediatelyas it strikes the screen. In such case, it is not necessary to rotatethe screen. It is also possible 't'o utilize a separate gas burner forincinerating the lint, but this approach is not as economical as thatdisclosed because additional controls and pilots are required.

It will be obvious, of course, that when the temperature in the area ofthe screen is raised to the ignition temperature of the lint, that therelative humidity of the gases discharged from the drier will belowered. Therefore, the air and combustion gases which are dischargedfrom the drier to the atmosphere outside the room in which the drier islocated are relatively dry (above their dew point) and condensationoccurs outside rather than in the ductwork of the drier Where it mightcause rusting.

Instead of hot gases or electrical heating elements as the heat source,it is possible 'to heat the lint particles by means of radiant energywhich will heat the particles without heating the gas stream.

Other modifications in the apparatus of the invention will occur tothose skilled in the art without departing from the scope of theappended claims.

This application is a continuation-in-part of my copending applicationentitled Improved Clothes Drier, Serial No. 420,998, filed April 5,1954, now abandoned.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a clothes drier having a drum compartment and a rotatable drummounted therein for tumbling the clothes, an air inlet duct connectingto said compartment, a gas burner mounted within said inlet duct, anexit duct leading from said compartment for discharging lintandmoisture-laden gas therefrom, a screen rotatably mounted within saidexit duct, a 'by-pass tube having one end mounted within said exit ductadjacent said screen and the opposite end mounted within said inlet ductadjacent said gas burner, and an exhaust fan in said exit ductdownstream of said screen for advancing the gas through the drier anddrawing hot gases from the gas burner through the by-pass tube tomaintain said one end of the tube at a temperature above the ignitionpoint of the lint.

2. In a clothes drier having a drum compartment and a rotatable drummounted therein for tumbling the clothes,

4 an air inlet duct connecting to said compartment, a gas burner mountedwithin said inlet duct, an exit duct leading from said compartment fordischarging lintand moistureladen gas therefrom, a screen rotatablymounted within said exit duct, a by-pass tube having one end mountedwithin said exit duct adjacent said screen and the opposite end mountedwithin said inlet duct adjacent said gas burner, means mounted withinthe duct for preventing the lint from flowing around the screen, and anexhaust fan in said exit duct downstream of said screen for advancingthe gas through the drier and drawing hot gases from the gas burnerthrough the by-pass tube to maintain said one end of the tube at atemperature above the ignition point of the lint.

3. In a clothes drier having a drum compartment and a rotatable drummounted therein for tumbling the clothes,

an air inlet duct connecting to said compartment, a gas burner mountedwithin said inlet duet, an exit duct leading from said compartment fordischarging lintand moisture-laden gas therefrom, a circular screenrotatably mounted within said exit duct, a power source for rotatingsaid screen at a rate of about one revolution per minute, a by-pass tubehaving one end mounted within said exit duct, said end having anelongated opening disposed parallel to a radius of said screen andslightly spaced therefrom, the opposite end mounted within said inletduct adjacent said gas burner, and an exhaust fan in said exit ductdownstream of said screen for advancing the gas through the drier anddrawing hot gases from the gas burner through the by-pass tube tomaintain said one end of the tube at a temperature above the ignitionpoint of the lint.

4. The clothes drier of claim 3 in which the exit duct contains meansfor preventing the lint from flowing around the screen.

' 5. The clothes drier of claim 2 in which the exit duct contains afrusto-conical sleeve mounted upstream of the screen with its smallerend facing the screen to direct the flow of gas through the duct awayfrom the walls of the duct toward the center of the screen.

6. A clothes drier comprising a compartment for contacting wet clotheswith heated air, an exit duct leading from said compartment fordischarging lintand moistureladen gas therefrom, a disc-like screenrotatably mounted within said duct in a plane normal to the flow of gastherethrough, a concentrated source of heat mounted within said exitduct adjacent said screen to maintain a sector of said screen above theignition point of the lint in the gas, and means for rotating saidscreen with respect to said heat source to incinerate the lint as it istrapped by the screen.

7. The clothes drier of claim 6 in which the the exit duct containsdeflecting means for preventing the lint from flowing past said screen.

References Cited in the file of this patent UNITED STATES PATENTS2,177,258 Jare Oct. 24, 1939 2,486,058 Patterson et al Oct. 25, 19492,521,465 Leon Sept. 5, 1950 2,611,192 Huebsch Sept. 23, 1952 FOREIGNPATENTS 620,906 Great Britain Mar. 31, 1949

